From d9a172fdb42a02d740d2c18fe535c512c9aa8cc3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Niels=20M=C3=B6ller?= <nisse@lysator.liu.se>
Date: Mon, 20 Jun 2011 14:17:16 +0200
Subject: [PATCH] Comment fix, and (invariant) argument reorder in SBOX1.
Rev: nettle/serpent-encrypt.c:1.12
---
serpent-encrypt.c | 25 +++++++++++++++++++++++--
1 file changed, 23 insertions(+), 2 deletions(-)
diff --git a/serpent-encrypt.c b/serpent-encrypt.c
index a64a2ef6..03ba0de0 100644
--- a/serpent-encrypt.c
+++ b/serpent-encrypt.c
@@ -96,7 +96,28 @@
/* FIXME: Arrange for some overlap between inputs and outputs? */
/* S1: 15 12 2 7 9 0 5 10 1 11 14 8 6 13 3 4 */
-#define SBOX1(x0, x1, x2, x3, y0, y1, y2, y3) \
+/* Original single-assignment form:
+
+ t01 = x0 | x3; 0
+ t02 = x2 ^ x3; 0
+ t03 = ~ x1; 0
+ t04 = x0 ^ x2; 0
+ t05 = x0 | t03; 0
+ t06 = x3 & t04; 0
+ t07 = t01 & t02; 0
+ t08 = x1 | t06; 0
+ y2 = t02 ^ t05; 0
+ t10 = t07 ^ t08; 0
+ t11 = t01 ^ t10; 0
+ t12 = y2 ^ t11; 0
+ t13 = x1 & x3; 0
+ y3 = ~ t10;
+ y1 = t13 ^ t12; 0
+ t16 = t10 | y1; 0
+ t17 = t05 & t16; 0
+ y0 = x2 ^ t17; 0
+*/
+#define SBOX1(x0, x1, x2, x3, y0, y1, y2, y3) \
do { \
y1 = x0 | x3; \
y2 = x2 ^ x3; \
@@ -112,7 +133,7 @@
x0 ^= y2; \
y1 = x1 & x3; \
y1 ^= x0; \
- x3 = y3 | y1; \
+ x3 = y1 | y3; \
y3 = ~ y3; \
y0 &= x3; \
y0 ^= x2; \
--
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